Nancy L Fleischer1
, Ann M Weber2
, Susan Gruber2
, Karina Z Arambula2
, Maya Mascarenhas2
, Jessica A Frasure2
, Constance Wang2
and S Leonard Syme3 
1
Center for Social Epidemiology and Population Health, Department of Epidemiology, University of Michigan, 1214 South University Avenue, 2nd Floor, Ann Arbor, MI 48104-2548, USA
2
Division of Epidemiology, School of Public Health, University of California, Berkeley, 140 Warren Hall, MC 7360, Berkeley, CA 94720-7360, USA
3
Division of Epidemiology, Division of Community Health & Human Development, School of Public Health, University of California, Berkeley, 140 Warren Hall, MC 7360, Berkeley, CA 94720-7360 USA